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Circuit to detect presence of a single RF frequency ?

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Externet

Externet

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Hi.
-Detection here not meaning to demodulate-
Detection as to know if 10.7MHz ± 100KHz is present on an existing receiver circuit node, to turn a LED on. How should be done ? Any dedicated IC or portion of such that does/could do it ?
 

A simple amplifier then a ceramic 10.7MHz filter following a amplifier+comparator will turn-on the LED.
Even an OPAMP may work with a appropriate circuit combination.There are many choices..
 

I don't know how can a LED turn on with such a high frequency, I think a mixer + 10MHz oscillator + low-pass filter + amplifier rather capable.
SA612 could be good because it contains mixer and oscillator.
 

Use a PLL and connect the LED to the lock indicator. By changing the VCO components you can set the center frequency and by changing the loop components you can set the lock bandwidth.

Brian.
 

BigBoss said:
A simple amplifier then a ceramic 10.7MHz filter following a amplifier+comparator will turn-on the LED.
Even an OPAMP may work with a appropriate circuit combination.There are many choices..
Click to expand...

i would modify this...ceramic filter, amplifier with 15 db gain at 10.7 MHz, another ceramic filter, then a schottky diode detector. The DC output of the detector can drive a comparator with a TTL output, that you could add a resistor limited LED to.

by using TWO ceramic filters...you can get almost 60 dB rejection of other frequencies.
 

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